16502 on Audi: How to Diagnose & Fix
Engine Coolant Temperature Sensor (G62): Signal too High
1 Audi model · 1 documented issue · $30-$180 repair
16502 on Audi by model: symptoms, diagnosis and fix
The original black-housing dual coolant temperature sensor (G62) mounted in the coolant flange at the back of the cylinder head develops cracks and fails internally. The temperature sensor G2 (also known as G62) for the gauge has likely failed and is relatively easy to fix; it is located in the coolant flange at the back of the cylinder head and the early square-connector style and later elongated D-shaped black connector sensors are known problematic units. When it fails the ECU sees an implausible coolant temperature, leading to cold starting difficulties at low temperatures, poor idle and acceleration during warm up as well as an erratic or dead temperature gauge.
Common Symptoms
- erratic or dead coolant temperature gauge
- hard cold starts
- rough idle during warm-up
- poor fuel economy
- rich-running condition
- check engine light
How to Fix
Scan with VAG-COM/VCDS for fault 17664 / 16502 (P0118) and bench-test the sensor's resistance. From Bentley, the G62 test procedure: allow engine to cool to room temp (68F/20C), disconnect ECT sensor, connect multimeter to terminals 1 and 2; resistance must be 1500 to 3000 ohms — if not, replace the ECT. Replace with the updated green-top OEM sensor (part 059 919 501A) along with the retaining clip (032 121 142) and O-ring; replacing this sensor resolves running issues for many owners who are still using the original black sensor which had a high failure rate. Part is ~$25-40, DIY 30 minutes; shop labor brings total to ~$80-180.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Engine Coolant Temperature SensorCross-refTSE 1D
Fitment confirmed against the ShowMeTheParts catalog for this vehicle's year and engine.
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Sources for this issue (1)
16502 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does 16502 mean on a Audi?
16502 stands for "Engine Coolant Temperature Sensor (G62): Signal too High." VAG/VCDS fault code 16502 corresponds to OBD-II code P0118 (Ross-Tech address 000280). It indicates the engine control module detected an abnormally high voltage signal from the Engine Coolant Temperature (ECT) sensor G62. High voltage is read as an implausibly cold engine (often colder than ambient), typically caused by an open circuit or failed sensor, and can disrupt cold-start fueling, idle, and the cooling-fan/warm-up strategy. On Audi it is documented across 1 model: A4.
What are the most common causes of 16502?
The most common causes of 16502 are: Faulty engine coolant temperature sensor (G62) reading out of range, Open or broken wiring in the ECT sensor signal circuit, Corroded, loose, or damaged sensor connector / poor ground, Loss of ground reference to the sensor, Low coolant level or air in the cooling system affecting the sensor, Failed or faulty engine control module (rare). The specific cause varies by vehicle.
How much does it cost to fix 16502 on a Audi?
Published repair estimates on Audi range from $30 to $180 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for 16502 on a different make?
View 16502 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.